Methods of identifying responders to dopamine agonist therapy

ABSTRACT

The present invention is directed to a method of identifying patients to be treated by dopamine agonist therapy comprising the step of analyzing a plasma or urine sample from said patient for concentrations of norepinephrine (NE), norepinephrine metabolites (NE metabolites), dopamine, dopamine metabolites, serotonin, serotonin metabolites, or fasting triglycerides, wherein one or more of: (a) NE metabolites, (b) NE/NE metabolites:dopamine/dopamine metabolites, (c) NE and serotonin, (d) NE/NE metabolites and serotonin, (e) NE and serotonin metabolites, (f) NE/NE metabolites and serotonin metabolites, or (g) NE is/are greater than about 30% over normal level; or dopamine/dopamine metabolites are less than about 30% below normal; or fasting triglycerides are greater than about 150 mg/dl and/or said patient has blood pressure of greater than about 135/85 mm Hg. The present invention is also directed to treating identified patients with dopamine agonist therapy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of U.S. Ser. No.11/086,937 filed Mar. 22, 2005, which claims the benefit of U.S.Provisional Application Ser. No. 60/556,309 filed Mar. 25, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method for identifying individuals sufferingfrom metabolic disorders such as diabetes, pre-diabetes, MetabolicSyndrome, or obesity, who will respond to dopamine agonist therapy. Moreparticularly, this invention relates to testing bodily fluids such asplasma or urine samples of individuals suffering from the abovedisorders to determine if those individuals will respond favorably todopamine agonist therapy.

2. Description of the Related Art

Metabolism is a complex orchestration of biochemical processes amongcells and tissues of the body all working in concert to ensure thesurvival of the organism as a whole. The central nervous system plays amajor role in integrating these metabolic activities to maintain normalbiological homeostasis within the body. Environmental and geneticperturbations to this central nervous system control of metabolism canmanifest as a range of metabolic disorders. Additionally, sincemetabolic processes have profound effects on the entire body, diseasesand disorders affecting metabolism generally affect other areas of thebody as well. For example, individuals suffering from Type 2 diabetesoften experience problems with other body organs and systems. Typically,plasma glucose levels are elevated in Type 2 diabetes as a result of thebody's resistance to the glucose-lowering effects of a hormone calledinsulin. Type 2 diabetes is associated with damage to various organssuch as the eyes, nerves, and kidneys. The disease is also associatedwith substantially increased risk for cardiovascular disease, theleading cause of death in Type 2 diabetics. The prevalence of Type 2diabetes is reaching epidemic proportions in the United States andaround the world.

To be diagnosed with Type 2 diabetes, an individual must have a fastingplasma glucose level greater than or equal to 126 mg/dl or a 2-hour oralglucose tolerance test (OGTT) plasma glucose value of greater than orequal to 200 mg/dl (Diabetes Care 26: S5-S20, 2003). A related conditioncalled pre-diabetes is defined as having a fasting glucose level ofgreater than 100 mg/dl but less than 126 mg/dl or a 2-hour OGTT plasmaglucose level of greater than 140 mg/dl but less than 200 mg/dl.Mounting evidence suggests that the pre-diabetes condition may be a riskfactor for developing cardiovascular disease (Diabetes Care 26:2910-2914, 2003).

Metabolic Syndrome, also referred to as Syndrome X, is another metabolicdisorder that affects other pathways and systems in the body.Originally, Metabolic Syndrome was defined as a cluster of metabolicdisorders (including obesity, insulin resistance, hypertension, anddyslipidemia primarily hypertriglyceridemia), that synergize topotentiate cardiovascular disease. More recently, the U.S. NationalCholesterol Education Program has classified Metabolic Syndrome asmeeting three out of the following five criteria: fasting glucose levelof at least 110 mg/dl, plasma triglyceride level of at least 150 mg/dl(hypertriglycerdemia), HDL cholesterol below 40 mg/dl in men or below 50mg/dl in women, blood pressure at least 130/85 mm Hg (hypertension), andcentral obesity, with central obesity being defined as abdominal waistcircumference greater than 40 inches for men and greater than 35 inchesfor women. The American Diabetes Association estimates that 1 in every 5overweight people suffer from Metabolic Syndrome.

While these disorders and diseases are related, it is clear that theyhave individual and distinct pathologies. For that reason, drugs used totreat one disorder may not be effective against another disorder. Forinstance, drugs that are effective in treating Type 2 diabetes orpre-diabetes have little to no effect on Metabolic Syndrome.Additionally, certain drugs used to treat Type 2 diabetes orpre-diabetes may increase blood pressure (hypertension) or cause weightgain in the individuals taking the medication. For example,thiazolidinediones used in the treatment of Type 2 diabetes causesweight gain and have marginal effects on hypertension. Anotheranti-diabetic agent, metformin, also has marginal effects onhypertension and hypertriglyceridemia. Insulin, which is a hormone usedto treat Type 2 diabetes, can potentiate hypertension and weight gain.Individuals suffering from metabolic disorders carry an increased riskof cardiovascular disease as a result of their hypertension and obesity.Therefore, side effects such as hypertension and weight gain havedamaging effects on those individuals. Consequently, those individualscannot take commonly prescribed medication to control their metabolicdisorders.

Dopamine agonist therapy has been effective in reducing hyperglycemia,glucose intolerance, hyperinsulinemia, insulin resistance, and/or plasmalipid levels in mammals, including humans. Dopamine agonist therapy hasalso been found to be an effective therapy for some individualssuffering from metabolic disorders. However, not all individuals respondwell to these therapies. For example, treatment of Type 2 diabetics withbromocriptine, a dopamine agonist, produces a bimodal distribution ofresponses in terms of improving glycemic control over a 24 weektreatment period when “responders” are defined as those individuals thatreduce percent glycosylated hemoglobin Alc (HbAlc) level by 0.3 withinan 8 week period from the initiation of dopamine agonist treatment. Theaverage percent HbAlc reduction among such responders was −0.63 and thisgroup represented 65% of the total treated population. Among theremaining 35% of the treated population (non-responders), the averagepercent HbAlc change was approximately +0.4 (Exp. Opin. Invest. Drugs8:1683-1707, 1999). Clearly, using this criteria, there is a bimodaldistribution of responses to dopamine agonist therapy among these Type 2diabetic individuals.

As with all medical therapies, it is a goal to minimize exposure tounnecessary or inappropriate treatment, as well as reduce or eliminatethe risk of unwanted side effects. It has been found that dopamineagonist therapy reduces or eliminates unwanted side effects that othermedications for the treatment of a metabolic disorder may cause. Thetreatment would be more beneficial if there was a method to identifyindividuals who would respond to the dopamine agonist therapy.

A variety of treatments are available for diseases associated withobesity, including Type 2 Diabetes. For example, U.S. Pat. No. 6,506,799discloses methods of treating cardiovascular diseases, dyslipidemia,dyslipoproteinemia, and hypertension comprising administering acomposition comprising an ether compound.

U.S. Pat. No. 6,441,036 discloses fatty acid analogous which can be usedfor the treatment and/or prevention of obesity, fatty liver andhypertension.

U.S. Pat. No. 6,410,339 discloses use of cortisol agonist for preparinga system for diagnosis of the Metabolic Syndrome and related conditionsas belly fatness, insulin resistance including increased risk ofdeveloping senile diabetes, i.e., diabetes type II, high blood fats andhigh blood pressure, in which system the dose of cortisol agonist is inan interval where a difference is obtained in the inhibitory effect ofthe autoproduction of cortisol in individuals suffering from theMetabolic Syndrome, compared to normal values.

U.S. Pat. No. 6,376,464 discloses peptides and peptide analogues thatmimic the structural and pharmacological properties of human ApoA-I. Thepeptides and peptide analogues are useful to treat a variety ofdisorders associated with dyslipidemia.

U.S. Pat. No. 6,322,976 discloses, among other things, methods ofdiagnosing a disease associated with a defect in insulin action, glucosemetabolism, fatty acid metabolism, and/or catecholamine action bydetecting a mutation in the CD36 gene.

U.S. Pat. No. 6,197,765 discloses a treatment for Metabolic Syndrome(syndrome-X), and resulting complications, by administration ofdiazoxide.

U.S. Pat. No. 6,166,017 discloses a method for the medical treatment ofdiabetes mellitus type II and for counteracting the risk factors formingpart of the Metabolic Syndrome by administration of ketoconazole.

U.S. Pat. No. 6,040,292 discloses methods for the treatment of diabetesmellitus, including type I, type II, and insulin resistant diabetes(both type I and type II). The methods of the invention employadministration of rhIGF-I/IGFBP-3 complex to a subject suffering fromthe symptoms of diabetes mellitus. Administration of rhIGF-I/IGFBP-3 toa subject suffering from the symptoms of diabetes mellitus results inamelioration or stabilization of the symptoms of diabetes.

U.S. Pat. No. 5,877,183 discloses methods for the regulation andmodification of lipid and glucose metabolism, but not MetabolicSyndrome, by administering to a subject a dopamine D1 agonist,optionally in combination with a dopamine D2 agonist, an alpha-1adrenergic antagonist, an alpha-2 adrenergic agonist, or a serotonergicinhibitor, or optionally in combination with a dopamine D2 agonistcoadministered with at least one of alpha-1 adrenergic antagonist, analpha-2 adrenergic agonist, or a serotonergic inhibitor, and furtheradministering the subject a serotonin 5HT_(1b) agonist. It is well knownthat dopamine agonists function to both activate and deactivate dopaminereceptors and thereby reduce dopaminergic neuronal activity.

U.S. Pat. No. 5,741,503 discloses methods for regulating or amelioratinglipid metabolism which comprise administration or timed administrationof inhibitors of dopamine beta hydroxylase (DBH). However, the focus ofthis technology is reduction in noradrenergic neuronal activity levelonly and does not increase dopaminergic neuronal activity inasmuch asDBH is not present in dopaminergic neurons that are anatomicallydistinct from noradrenergic neurons where DBH resides.

From a clinical point of view, what is needed is a method of identifyingprior to the initiation of treatment, those individuals in need of suchtreatment that are most likely to respond to dopamine agonist therapy interms of improving symptoms of Type 2 diabetes, pre-diabetes, orMetabolic Syndrome. The ability to identify responders to dopamineagonist therapy, and particularly among Type 2 diabetics, pre-diabetics,and/or Metabolic Syndrome subjects prior to exposure to the therapyitself would greatly increase the benefit-to-risk ratio for such therapyamong treated subjects, which is the goal of all medical interventions,treatments, and therapies. Identification of responders would minimizethe risk of needless exposure or inappropriate treatment in lieu ofother more appropriate treatment strategies among those individualsclassified as non-responders to dopamine agonist therapy in whom, onaverage, no clinical benefit is expected. The present invention isbelieved to be an answer to the above needs.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the present invention is directed to a method ofidentifying patients to be treated by dopamine agonist therapycomprising the step of analyzing a plasma or urine sample from saidpatient for concentrations of norepinephrine (NE), norepinephrinemetabolites (NE metabolites), dopamine, dopamine metabolites, serotonin,serotonin metabolites, or fasting triglycerides wherein one or more of:(a) NE metabolites, (b) NE/NE metabolites: dopamine/dopaminemetabolites, (c) NE and serotonin, (d) NE/NE metabolites and serotonin,(e) NE and serotonin metabolites, (f) NE/NE metabolites and serotoninmetabolites, or (g) NE, is/are greater than about 30% over normal level;or dopamine/dopamine metabolites are less than about 30% below normal;or fasting triglycerides are greater than about 150 mg/dl and/or saidpatient has blood pressure of greater than about 135/85 mm Hg.

In another aspect, the present invention is directed to a method oftreating a patient suffering from a metabolic condition, comprising thesteps of:

-   -   (a) identifying patients to be treated by dopamine agonist        therapy according to the above procedure, and    -   (b) administering to the identified patients a pharmaceutically        effective regimen of dopamine agonist therapy;        -   wherein the metabolic condition is selected from the group            consisting of Type 2 diabetes, pre-diabetes, Metabolic            Syndrome, obesity, hyperglycemia, glucose intolerance,            hyperinsulinemia, insulin resistance, elevated plasma lipid            levels, and combinations thereof.

These and other aspects will be described in more details in thefollowing detailed description of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the method of the present invention, it has beensurprisingly discovered that it is possible to identify patients thatare suffering from Type 2 diabetes, pre-diabetes, Metabolic Syndrome, orobesity, and determine if they are good candidates (termed “responders”)for dopamine agonist therapy. These responders have a higher likelihoodof successful treatment, generally as a percent of the population in therange of 70% or better as compared to 25-35% among a random selection ofsuffering patients. Identification of patients who will respond well todopamine agonist therapy prevents inappropriate and/or unnecessarytreatment to some individuals.

As indicated above, the present invention is a method of identifyingpatients to be treated by dopamine agonist therapy comprising the stepof analyzing a plasma or urine sample from said patient forconcentrations of norepinephrine (NE), norepinephrine metabolites (NEmetabolites), dopamine, dopamine metabolites, serotonin, serotoninmetabolites, or fasting triglycerides. If one or more of: (a) NEmetabolites, (b) NE/NE metabolites: dopamine/dopamine metabolites, (c)NE and serotonin, (d) NE/NE metabolites and serotonin, (e) NE andserotonin metabolites, (f) NE/NE metabolites and serotonin metabolites,or (g) NE is/are greater than about 30% over normal level; ordopamine/dopamine metabolites are less than about 30% below normal; orfasting triglycerides are greater than about 150 mg/dl and/or saidpatient has blood pressure of greater than about 135 (Systolic)/85(Diastolic) mm Hg, the individual is identified as a responder todopamine agonist therapy.

As a preliminary step, it may be desirable to identify the metabolicdisorder of the individual (e.g., Type 2 diabetes, pre-diabetes,Metabolic Syndrome, obesity, hyperglycemia, glucose intolerance,hyperinsulinemia, insulin resistance, elevated plasma lipid levels,etc.) with appropriate clinical measures of plasma glucose, insulin,lipids, glucose tolerance, blood pressure, obesity, and the like. Thesedeterminations may be made by analytical methods and tests well known inthe art, for example spectrophotometry, radioimmunoassay, andanthropomorphic measurements.

A urine or plasma sample from the patient is analyzed using conventionaltechniques such as spectrophotometry, high pressure liquidchromotography (HPLC), and the like. Preferably, the urine or plasmasample is obtained in the morning, after rising from sleep. The analysisshould measure the concentrations of the following compounds:norepinephrine (NE), norepinephrine metabolites (NE metabolites),dopamine, dopamine metabolites, serotonin, serotonin metabolites, and/orfasting triglycerides. In one embodiment, the absolute concentration ofcompounds or combinations of compounds may be used, such as NEmetabolites, NE and serotonin, NE/NE metabolites and serotonin, NE/NEmetabolites and serotonin metabolites, or NE and serotonin metabolites.In another embodiment, the ratio of two of the concentrations ofcompounds may be used, such as NE/NE metabolites: dopamine/dopaminemetabolites. An indication of a favorable response to dopamine agonisttherapy is indicated when one or more of these values are greater thanabout 30% over normal level.

In another embodiment, an indication of a favorable response to dopamineagonist therapy is indicated when dopamine or dopamine metabolites areless than about 30% below normal.

In another embodiment, an indication of a favorable response to dopamineagonist therapy is indicated when fasting triglycerides are greater thanabout 150 mg/dl and/or the patient has blood pressure of greater thanabout 135/85 mm Hg.

Once responders are identified, treatment of their metabolic disorderwith a dopamine agonist may begin. Those individuals identified asresponders are anticipated to react well to the dopamine agonisttherapy.

The dopamine agonist treatment therapy may be administered by any methodknown in the art, for example administration of bromocriptine orpharmaceutical formulations thereof.

A positive response to dopamine agonist therapy can be identified bysimple tests performed on patients undergoing the treatment. In oneembodiment, a positive response to the therapy in patients with Type 2diabetes is indicated by the decline from baseline of HbAlc of at least0.5 over a 12-24 week treatment period. In another embodiment, apositive response in patients with pre-diabetes is indicated by afasting glucose level reduced below about 110 mg/dl or the 2-hour OGTTreduced below about 175 mg/dl. In yet another embodiment, patients withMetabolic Syndrome who have a positive response to the dopamine agonisttherapy have improvements by at least 3-5% of any three of glucosetolerance, fasting plasma glucose, postprandial plasma glucose, plasmatriglyceride, plasma HDL-cholesterol, blood pressure, or obesity.

While the invention has been described in combination with embodimentsthereof, it is evident that many alternatives, modifications andvariations will be apparent to those skilled in the art in light of theforegoing description. Accordingly, it is intended to embrace all suchalternatives, modifications and variations as fall within the spirit andbroad scope of the appended claims. All patent applications, patents,and other publications cited herein are incorporated by reference intheir entireties.

1. A method of identifying patients to be treated by dopamine agonisttherapy comprising the steps of: analyzing a plasma or urine sample fromsaid patient for concentrations of norepinephrine (NE), norepinephrinemetabolites (NE metabolites), dopamine, dopamine metabolites, serotonin,serotonin metabolites, or fasting triglycerides, wherein one or more of:a) NE metabolites, b) NE/NE metabolites: dopamine/dopamine metabolites,c) NE and serotonin, d) NE/NE metabolites and serotonin, e) NE andserotonin metabolites, f) NE/NE metabolites and serotonin metabolites,or g) NE, is/are greater than about 30% over normal level; ordopamine/dopamine metabolites are less than about 30% below normal; orfasting triglycerides are greater than about 150 mg/dl and/or saidpatient has blood pressure of greater than about 135/85 mm Hg.
 2. Themethod of claim 1, wherein said patient is suffering from a conditionselected from the group consisting of Type 2 diabetes, pre-diabetes,Metabolic Syndrome, obesity, hyperglycemia, glucose intolerance,hyperinsulinemia, insulin resistance, elevated plasma lipid levels, andcombinations thereof.
 3. A method of treating a patient suffering from ametabolic condition, comprising the steps of: (a) identifying patientsto be treated by dopamine agonist therapy according to claim 1, and (b)administering to said identified patients a pharmaceutically effectiveregimen of dopamine agonist therapy; wherein said metabolic condition isselected from the group consisting of Type 2 diabetes, pre-diabetes,Metabolic Syndrome, obesity, hyperglycemia, glucose intolerance,hyperinsulinemia, insulin resistance, elevated plasma lipid levels, andcombinations thereof.
 4. The method of claim 3, wherein saidpharmaceutically effective regimen of dopamine agonist therapy comprisesadministration of bromocriptine.